Heat the oven to 350°F (175°C). Line a 12-cup muffin pan with paper liners, then place one whole Golden Oreo in the bottom of each liner.

Whisk the flour, baking powder, and salt together in a medium bowl. This distributes the leavening and seasoning evenly before the dry mixture is added to the batter.

Beat the softened butter and granulated sugar for about 2–3 minutes, until the mixture looks light and fluffy. Add the eggs one at a time, beating well after each addition, then mix in the vanilla.

Add the dry ingredients in two or three additions, alternating with the room-temperature milk. Mix only until the batter is combined, since extended mixing can make the cupcakes dense.

Fold in the six coarsely chopped or crushed Golden Oreos with a spatula. Use gentle strokes so the cookie pieces remain distributed through the batter instead of breaking down completely.

Divide the batter among the prepared liners, filling each about two-thirds full. This leaves enough room for the cupcakes to rise without spilling over the edges.

Bake for 18–22 minutes, or until the tops spring back lightly and a toothpick inserted into the cake portion comes out clean. Avoid testing directly through a cookie piece, which can make the toothpick look moist even when the cake is done.

Cool the cupcakes in the pan for 5 minutes, then transfer them to a wire rack. Let them cool completely before frosting so the buttercream stays thick and holds its shape.

For the buttercream, beat the softened butter for 2–3 minutes until smooth and pale. Gradually beat in the sifted confectioners’ sugar, then add the vanilla and 2 tablespoons of cream or milk.

Beat the frosting for another 2–3 minutes, adding the remaining liquid as needed for a spreadable or pipeable consistency. Mix in the finely crushed Golden Oreos, then pipe or spread the frosting onto the cooled cupcakes and garnish with mini cookies or cookie halves.